Response would be correct, as in response to environment.
Answer:
its a and b for this anwser
<span>an organic compound made by replacing the hydrogen of an acid by an alkyl or other organic group. Many naturally occurring fats and essential oils are esters of fatty acids. SOURCE: GOOGLE
I sourced it so please dont report</span>
If two populations of birds stop interbreeding because of a difference in song patterns this would be described as behavioral isolation.
